254,274 entries

Classification

Every patent office files each application under one or more codes from a shared scheme of subjects. It is the one description of what a patent is about that holds across countries, languages and decades, which is what lets a Chinese patent and an American one be counted in the same column.

Sections
9
Classes
137
Subclasses
681
Main groups
9,868

Five steps, from the general to the exact

A code is read from the left, and each step narrows the subject. The lithium-ion battery is the example. An application usually carries several codes, one for each aspect of the invention.

StepCodeSubject
SectionHElectricity
ClassH01Electric elements
SubclassH01MBatteries and fuel cells
Main groupH01M 10/00Secondary cells
SubgroupH01M 10/0525Lithium-ion batteries

Two schemes on one ladder

The International Patent Classification is the common base. The Cooperative Patent Classification is the same ladder cut finer, with about three times as many entries. Down to the subclass the two agree almost everywhere, so a patent is counted here at the subclass on whichever code it carries.

International (IPC)Cooperative (CPC)
Kept byThe World Intellectual Property Organization, under the Strasbourg Agreement of 1971The European and United States patent offices, jointly, since 2013
SizeAbout 80,000 entries254,274 entries
SectionsA to HA to H, and Y for tags that cut across the rest
On Chinese publications100%48%
On United States publications90%96%

Share of publications at each office that carry at least one code in each classification. Designs carry neither; they are classified under the Locarno scheme.

The scheme, with its weight in each country

The share of each country's patent families, 2015 to 2024, that carry a code in each section, class and subclass: American inventions above, Chinese below. Shares add to more than 100 per cent because an invention can sit in several places. Bars are scaled within each step of the ladder.

United StatesChina